This invention relates to the production of oil, gas or water from wells and more particularly to apparatus that is useful for measuring conditions existing at a specific depth in the well and is capable of being run into a well, set, and retrieved from the well on a wire line.
Occasionally it is necessary to run a tool into a well and set the tool to isolate that part of the well below the tool from that part of the well above the tool. For example, it may be desirable to measure the temperature or pressure of well fluids at a specific depth in the wall. On some occasions it is desirable to direct all of the flow upwardly through a well at a selected depth through a flow meter to obtain information of value in production of fluids from the well. After the testing of the well has completed, the tools or instruments used in the testing are removed either to remove obstructions to flow or to permit running other tools into the well. It is desirable that the tools or instruments used in the testing be capable of being run into the well, set, operated and retrieved by wire line to leave the well in a fully open condition that existed prior to the testing.
Isolation of a lower portion of a well from a higher portion is ordinarily accomplished by setting a packer in the well. Many packers are mechanically set by rotating a portion of the packer to cause a sleeve to move along threads and thereby exert forces against the ends of a sealing element that distort the sealing element to engage the inner wall of casing or other conduit in the well. To accomplish the relative rotation of parts of the packer, such packers ordinarily are run into the well on tubing and include a friction element that will engage the wall of casing or other conduit in which it is set to prevent rotation of the packer as the tubing on which it is run into the well is rotated. Another type of packer is run into the well on tubing and a plug dropped into the packer to prevent flow through its lower end. Thereafter, liquid is pumoed down the tubing to develop hydraulic pressure that moves piston-like elements that compress sealing elements to set the packer. Both the mechanically set packers and the hydraulically set packers require a rig for running tubing on which the packer is mounted into the well and removing it from the well after testing has been completed. If the testing is to extend over an appreciable period, the rig must either remain at the well during the testing or make a second trip for removal of the packer after the testing has been completed. If the packer is left in the well, it severely restricts the borehole opening and may interfere with subsequent production from the well. A mechanically set packer used to isolate the lower part of the well for a testing device is described in U.S. Pat. No. 2,702,474 of Johnston.
Wire line operated packers have been developed to avoid the cost of a derrick to run the packer and pull it when removal of the packer is desired. Such packers have a substantial length including slips and the sealing elements over which there is a very small clearance between the inner wall of the tubing and the packer. Because of the length of the wire line operated packers over which there is a very small clearance with the tubing, it is difficult to run the packers into tubing and often impossible to retrieve them. Bending, twisting or flattening of the tubing often prevents use of the wire line operated packers. Moreover, pitting, scoring or other damage to the tubing during use frequently prevents obtaining a seal which will allow the control needed for accurate test of the well.
Electrically operated packers have been developed for use with sensitive electrical instruments requiring an electric line. Such packers are described in U.S. Pat. Nos. 3,503,444 and 3,542,126 of Arthur L. Owen. The packers are run to the desired depth on an electric wire line. An electric motor in the packer is then utilized to compress sealing means and move them outwardly against the wall of the tubing or casing in which the packer is set. In some instances, a motor-driven pump is used to inflate a flexible bag-type packer. U.S. Pat. Nos. 3,503,444 and 3,542,126 describe testing tools for measuring conditions at a specific depth in a well that utilize an electric motor to set the packer. These packers are also quite long, have a very small clearance and, additionally, require electrical power for operation. Loss of power after the packer is set can be disastrous.